In the related art, there has been known an inductively coupled plasma generating apparatus which generates plasma inside a processing chamber by supplying a high frequency power to a spiral coil electrode disposed outside the processing chamber to generate a magnetic field inside the processing chamber.
In this plasma generating apparatus, the coil electrode is formed by a hollow tube made of a copper, and cooling water is circulated inside the hollow tube so that the coil electrode is suppressed from being heated to a high temperature due to the high frequency power supplied to the coil electrode (see, e.g., Japanese Laid-Open Patent Publication Nos. 2004-165345 and 2013-161874).